temperature sensor

Abstract

Temperature sensor (40) for a battery cell (10) of a rechargeable battery, comprising: a resistive sensor element (46), a first electrode (42) and a second electrode (44); wherein the resistive sensor element (46), the first electrode (42) and the second electrode (44) are attached to a porous separator (20); wherein the porous separator (20) is arranged between an anode (12) and a cathode (14) of the battery cell (10); wherein the resistive sensor element (46) is electrically connected in series between the first electrode (42) and the second electrode (44); wherein the resistive sensor element (46), the first electrode (42) and the second electrode (44) are attached to the separator (20) by physical vapor deposition; and wherein the resistive sensor element (46), the first electrode (42) and the second electrode (44) are porous.

Description

[0001] Rechargeable batteries are used in vehicles, power tools, stationary power supply systems, personal electronic devices, and other equipment, serving as portable electrical energy storage. Their charging, discharging, and lifespan characteristics are influenced by operating parameters such as battery temperature. Therefore, it is advantageous to monitor the temperature of a rechargeable battery accurately and precisely.

[0002] US 2013 / 0004811A1 describes a battery temperature sensor comprising a substrate and a thin-film resistive temperature detector (RTD).

[0003] DE 11 2010 003 272 T5 describes a battery cell which has a sensor platform with sensor elements.

[0004] US 2005 / 0 130 037 A1 describes a flat secondary battery in which the temperature rise (heat generation) during rapid charging / discharging can be measured.

[0005] The CN 2 07 883 840 U describes a lithium battery cell coating temperature measuring sensor.

[0006] JP 2008 - 192 495 A describes a method for determining an internal short circuit for a battery.

[0007] It can be considered a task to specify an improved temperature sensor.

[0008] The concepts described herein comprise a temperature sensor located within a battery cell of a rechargeable battery. The sensor cell includes a resistive sensor element, a first electrode, and a second electrode, all mounted on a porous separator positioned between the anode and cathode of the rechargeable battery. The resistive sensor element is electrically connected in series between the first and second electrodes, which are all mounted as foil layers on the separator. The resistive sensor element, the first electrode, and the second electrode are porous and have permeabilities of the same order of magnitude as the permeability of the separator.

[0009] According to the invention, a temperature sensor for a battery cell of a rechargeable battery comprises a resistive sensor element, a first electrode, and a second electrode, wherein the resistive sensor element, the first electrode, and the second electrode are mounted on a porous separator. The porous separator is arranged between an anode and a cathode of the battery cell. The resistive sensor element is electrically connected in series between the first electrode and the second electrode. The resistive sensor element, the first electrode, and the second electrode are mounted on the separator by physical vapor deposition and are porous.

[0010] In one embodiment, the resistive sensor element, the first electrode and the second electrode are made of a material consisting of gold, nickel or conductive carbon black.

[0011] In one embodiment, the resistive sensor element, the first electrode and the second electrode have permeabilities that are of the same order of magnitude as the permeability of the porous separator.

[0012] In one embodiment, the temperature sensor comprises a reference electrode integrated into the resistive sensor element, wherein the reference electrode is attached to the porous separator. The reference electrode is attached to the separator and is porous.

[0013] In one embodiment, the reference electrode is integrated into the resistive sensor element, which comprises a first resistance path and a second resistance path. The first resistance path is electrically connected in parallel to the second resistance path, with the first resistance path being resistance-symmetrical to the second resistance path. The reference electrode is connected to the first resistance path and to the second resistance path at a first junction. The first resistance path is electrically connected to the second resistance path at a second junction. The reference electrode includes an end section that is positioned between the first and the second resistance paths.

[0014] In one embodiment, the first resistance path is resistance-symmetrical to the second resistance path, wherein the first resistance path is a mirror image of the second resistance path.

[0015] In one embodiment, the first resistance path has the same geometric shape, cross-sectional area and path length as the second resistance path.

[0016] In one embodiment, the reference electrode is porous, including the reference electrode with a permeability that is of the same order of magnitude as the permeability of the porous separator. Fig. Figure 1 schematically shows an isometric exploded view of a battery cell. Fig. Figure 2 schematically shows a top view of a separator with a temperature sensor. Fig. Figure 3 schematically shows a top view of a temperature sensor and a reference electrode. Fig. Figure 4 shows a graphical calibration diagram for one embodiment of a temperature sensor.

[0017] Referring to the drawings, shows Fig. Figure 1, in accordance with the embodiments disclosed herein, schematically depicts a rechargeable battery cell 10, which may be an element of a battery pack or battery system. The battery pack or battery system may contain a plurality of battery cells 10 and may be used as an electrical energy source for a vehicle, a portable power tool, a personal electronic device, a computer system, a stationary device, and the like. In one embodiment, each of the battery cells 10 is configured as an electrochemical lithium-ion cell arranged to provide a specific voltage and / or current that can be used to operate an electromechanical device such as an electric machine or an actuator.Each of the battery cells 10 comprises electrochemical materials which may be in the form of an aqueous lithium ion solution containing electrolytes and / or electrodeactive materials which are responsible for the electrical activity therein.

[0018] The battery cell 10 comprises an anode 12, a cathode 14, a separator 20, a sensor shield 30, and a temperature sensor 40, enclosed in a housing 16 containing electrochemical materials. As shown, and in one embodiment, the battery cell 10 is arranged as a large-format pouch cell. In one embodiment, the temperature sensor 40 is electrically connected to a reference electrode 48. The separator 20 is arranged between the anode 12 and the cathode 14, physically separating them. The temperature sensor 40 is mounted on the separator 20. The sensor shield 30 is arranged between the temperature sensor 40 and an adjacent anode 12 or cathode 14. In another embodiment, and as shown, the temperature sensor 40 is mounted on the separator 20 opposite the anode 12, and the sensor shield 30 is arranged between the temperature sensor 40 and the anode 12.Alternatively, the temperature sensor 40 is mounted on the separator 20, which faces the cathode 14, and the sensor shield 30 is arranged between the temperature sensor 40 and the cathode 14. In one embodiment, and as shown, the anode 12, the cathode 14, the separator 20, and the sensor shield 30 are configured as planar devices arranged in parallel.

[0019] Separator 20 is a porous, permeable, or semi-permeable composite membrane containing a microporous substrate and a coating layer. The coating layer can be formed from a mixture of inorganic and / or organic particles and an aqueous or water-based polymeric binder. The coating layer can also be formed from filler material that enables or causes anisotropic electrical and / or thermal conductivity. For example, the coating layer can contain nanomaterials such as metallic, semi-metallic, or carbon-based nanoparticles, nanotubes, nanofibers, graphene sheets, or similar materials. Furthermore, certain fillers can be used to achieve enhanced structural properties. In addition to or instead of conductive fillers, structural fillers can be used, such as...Fibers, spheres, granules, or similar materials made of a ceramic material, such as silicate or borosilicate glass, or another suitable material. The coating layer may also contain a porous material such as polyolefin (e.g., polyethylene, polypropylene), a polyarene (e.g., polystyrene, polyphenylene sulfide), or similar, which allows the passage of lithium ions through the coating layer.

[0020] The temperature sensor 40 is attached to the separator 20 and comprises a resistive sensor element 46, a first electrode 42 and a second electrode 44.

[0021] In one embodiment, the resistive sensor element 46, the first electrode 42, and the second electrode 44 are made of gold. Alternatively, the resistive sensor element 46, the first electrode 42, and the second electrode 44 can be made of nickel, a conductive carbon black material, or another low-reactivity platinum group metal that is inactive in lithium-ion chemistry. The resistive sensor element 46, the first electrode 42, and the second electrode 44 can be made of any conductive material that can be rendered porous upon application to the separator 20 by sputtering or another deposition process and remains inactive in battery chemistry.

[0022] The resistive sensor element 46 is electrically connected in series between the first electrode 42 and the second electrode 44. First and second leads 43 and 45, respectively, are electrically connected to the first and second electrodes 42 and 44, respectively, and establish electrical connections to a monitoring controller 25. The temperature sensor 40 is applied to the separator 20 as a film layer by sputtering or another form of physical vapor deposition. Applying the temperature sensor 40 as a film layer makes it porous and permeable to ion flow, thus preventing interruption of lithium migration, which involves the passage of liquid-phase ion currents through the separator 20. The temperature sensor 40 is conductive and can be used to measure the temperature inside the battery cell 10.The measured temperature inside battery cell 10 can be extrapolated or otherwise used to estimate the temperature of a battery pack or battery system in which battery cell 10 is located.

[0023] With reference to the Fig. 2 and Fig. Section 3 now describes details regarding the temperature sensor 40 attached to the separator 20. The temperature sensor 40 is a resistive temperature sensor, which means that the temperature is determined in terms of the measured electrical resistance. Fig. Figure 4 graphically shows an example of a calibration diagram, representing the temperature on the horizontal axis 410 and the resistance on the vertical axis 420, with a temperature / resistance relationship 430 being shown. A linear regression can be determined and, in practice, reduced to a calibration that can be stored as a lookup table, executable equation, or in another form in the monitoring controller 25, which refers to Fig. As described in section 1, the monitoring controller 25 can be implemented. It can execute a control routine to measure the electrical resistance in the temperature sensor 40 and, based on this, determine the temperature in the battery cell 10.

[0024] Referring again to Fig. 2 and Fig. 3 The temperature sensor 40 comprises the resistive sensor element 46, the first electrode 42, and the second electrode 44. The resistance to the flow of electric charge in an element, e.g., the resistive sensor element 46, the first electrode 42, and the second electrode 44 of the temperature sensor 40, can be determined as a function of the overall length, cross-sectional area, and material of the element according to the following relationship: R=ρ(L / A) where: R is the total resistance. ρ is the specific resistance value of the material, L is the length of the element, and A is the cross-sectional area of ​​the element.

[0025] The relationship described with reference to Equation 1 can be used to design the temperature sensor 40 such that the resistance contributions of the first and second electrodes 42, 44 make minimal contributions to the total resistance of the temperature sensor 40, wherein the resistive sensor element 46 is designed to control the temperature-induced resistance change of the temperature sensor 40. This information can be used to calibrate the temperature sensor 40, including selecting a desired path for adjusting its sensitivity to temperature changes.

[0026] The first electrode 42 and the second electrode 44 can be arranged in thin layers with relatively large surface areas to minimize resistance and increase permeability. The permeabilities of the first and second electrodes 42, 44 are of the same order of magnitude as the permeability of the separator 20, thus ensuring that the lithium migration function of the separator 20 is not impaired. In one embodiment, the elements of the temperature sensor 40 are an order of magnitude thinner than other layers of the battery cell 10. In one embodiment, the temperature sensor 40 is fabricated as a thin-film temperature sensor with a thickness of 50 nm. The thin film has a low heat capacity, enabling it to respond quickly to temperature changes, including temperature changes caused by electrochemical activity.Due to the use of the sputter coating, the temperature sensor 40 is just as porous and permeable as the separator 20, which counteracts any disturbance of the ion current flow and provides a conductor for the reference electrode 48. The temperature sensor operates as a thermistor, with increased resistance corresponding to increased temperature. The total resistance is measured as a function of the temperature and the geometry of the sputter coating of the temperature sensor 40. Small cross-sectional areas with large path lengths dominate the resistance, so that the resistance of the overall system is approximately equal to the resistance of the intentionally thin regions connected to the resistive sensor element 46. Thus, the temperature is measured at the thin regions of the temperature sensor 40, i.e., at the resistive sensor element 46.The resistive sensor element 46 can be attached to a desired location on the separator 20 to monitor the temperature at the desired location in the battery cell 10. In one embodiment, the desired location can be near a geometric center point of the flat surface associated with the separator 20. In another embodiment, the desired location can be near a lower section of the flat surface associated with the separator 20. In yet another embodiment, the desired location can be near an upper section of the flat surface associated with the separator 20.

[0027] Design factors such as the position of the battery pack relative to the system in which it is used, and the associated heat transfer, can influence the position of the temperature sensor 40. Furthermore, the temperature sensor 40 can be located in one or a portion of the battery cells within a battery pack, and factors related to heat transfer within the battery pack can influence the position of the battery cell 10 containing the temperature sensor 40.

[0028] With reference to Fig. 3 now describe additional details regarding the temperature sensor 40 including the first and second electrodes 42, 44 and the reference electrode 48.

[0029] The reference electrode 48 is integrated into the resistive sensor element 46 of the temperature sensor 40. The resistive sensor element 46 comprises a first resistance path 53 and a second resistance path 54, wherein the first resistance path 53 is electrically connected in parallel with the second resistance path 54, the current flow through which is indicated by arrows. The reference electrode 48 is connected to the first resistance path 53 and to the second resistance path 54 at a first junction 51. Furthermore, the first resistance path 53 is electrically connected to the second resistance path 54 at a second junction 52. The reference electrode 48 projects between the first and second resistance paths 53, 54 and includes an end section 50 that is arranged between the first and second resistance paths 53, 54.

[0030] The first and second resistive paths 53, 54 are designed to be resistance-symmetric, i.e., the resistances of the first and second resistive paths 53, 54 are equivalent. In one embodiment, the first resistive path 53 is resistance-symmetric to the second resistive path 54 by being arranged as a mirror image of the second resistive path 54. This includes the first resistive path 53 having the same geometric shape, cross-sectional shape (including area and thickness), and path length as the second resistive path 54, and the first resistive path 53 being made of the same material as the second resistive path 54.The resistance symmetry and the associated symmetrical arrangement of the first and second resistance paths 53, 54 are used to minimize the electric current through the reference electrode 48 when the controller 45 operates for resistance measurement and thus for temperature determination.

[0031] The thin-film temperature sensor and reference electrode described here can be used within a cell stack in a large-format commercial cell or a small-format laboratory setup. The temperature sensor 40 serves the dual purpose of providing a reference electrode and a thermistor, with the separator serving as the support substrate. The thickness, path length, and path width of the porous thermistor can be varied in different applications to modify its resistance sensitivity to temperature changes in different areas of the separator. The symmetry minimizes fluctuations in the electrical currents near the reference electrode when temperature measurements are taken.

[0032] The term "controller" and related terms such as microcontroller, control module, module, control, control unit, processor and similar terms refer to one or more combinations of application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), electronic circuits, central processing units, e.g. microprocessors and associated non-transitory memory components in the form of storage and memory devices (read-only, programmable read-only, random access, hard disk drive, etc.).The non-transitory memory component is capable of storing machine-readable instructions in the form of one or more software or firmware programs or routines, combinational logic circuits, input / output circuits and devices, signal conditioning, buffer circuits, and other components that can be accessed and executed by one or more processors to provide a described functionality. Input / output circuits and devices include analog-to-digital converters and related devices that monitor sensor inputs, either at a preset sampling rate or in response to a triggering event. Software, firmware, programs, instructions, control routines, code, algorithms, and similar terms refer to sets of instructions executable by controllers, including calibrations and lookup tables.Each controller executes control routine(s) to provide the desired functionality. These routines can be executed at regular intervals, for example, every 100 microseconds during operation. Alternatively, the routines can be executed in response to a triggering event.

[0033] Communication between controllers, actuators, and / or sensors can occur via a directly wired point-to-point connection, a networked communication bus connection, a wireless connection, or another suitable communication link. This communication involves the exchange of data signals in a suitable form, such as electrical signals over a conductive medium, electromagnetic signals over air, optical signals over fiber optic cables, and the like. The data signals can include discrete analog or digitized analog signals representing sensor inputs, actuator commands, and communication between controllers.

[0034] The term "signal" refers to a physically perceptible indicator that transmits information and can be a suitable waveform (e.g., electrical, optical, magnetic, mechanical, or electromagnetic), such as direct current, alternating current, sine wave, triangle wave, square wave, vibration, and the like, which can propagate through a medium.

[0035] The terms "calibration," "calibrated," and related terms refer to a result or process that correlates a desired parameter with one or more perceived or observed parameters for a device or system. A calibration, as described here, can be reduced to a storable parameter table, a set of executable equations, or any other suitable form that can be used as part of a measurement or control routine.

[0036] A parameter is defined as a measurable quantity that represents a physical property of a device or other element, detectable by one or more sensors and / or a physical model. A parameter can have a discrete value, e.g., either "1" or "0", or it can have a continuously variable value.

Claims

[1] Temperature sensor (40) for a battery cell (10) of a rechargeable battery, comprising: a resistive sensor element (46), a first electrode (42) and a second electrode (44); wherein the resistive sensor element (46), the first electrode (42) and the second electrode (44) are attached to a porous separator (20); wherein the porous separator (20) is arranged between an anode (12) and a cathode (14) of the battery cell (10); wherein the resistive sensor element (46) is electrically connected in series between the first electrode (42) and the second electrode (44); wherein the resistive sensor element (46), the first electrode (42) and the second electrode (44) are attached to the separator (20) by physical vapor deposition; and wherein the resistive sensor element (46), the first electrode (42) and the second electrode (44) are porous. [2] Temperature sensor (40) according to claim 1, wherein the resistive sensor element (46), the first electrode (42) and the second electrode (44) are made of a gold, nickel or conductive carbon black material. [3] Temperature sensor (40) according to claim 1, wherein the resistive sensor element (46), the first electrode (42) and the second electrode (44) are porous, wherein the resistive sensor element (46), the first electrode (42) and the second electrode (44) have permeabilities that are of the same order of magnitude as the permeability of the porous separator (20). [4] Temperature sensor (40) according to claim 1, further comprising a reference electrode (48) which is integrated into the resistive sensor element (46); wherein the reference electrode (48) is attached to the porous separator (20); wherein the reference electrode (48) is attached to the separator (20) by physical vapor deposition; and wherein the reference electrode (48) is porous. [5] Temperature sensor (40) according to claim 4, wherein the reference electrode (48) which is integrated into the resistive sensor element (46) comprises: the resistive sensor element (46) with a first resistance path (53) and a second resistance path (54); wherein the first resistance path (53) is electrically connected in parallel with the second resistance path (54); wherein the first resistance path (53) is resistance-symmetrical to the second resistance path (54); wherein the reference electrode (48) is connected to the first resistance path (53) and to the second resistance path (54) at a first junction (51); wherein the first resistance path (53) is electrically connected to the second resistance path (54) at a second junction (52); and wherein the reference electrode (48) has an end section (40) which is arranged between the first and second resistance paths (53, 54). [6] Temperature sensor (40) according to claim 5, wherein the first resistance path (53) is resistance-symmetric to the second resistance path (54), wherein the first resistance path (53) is a mirror image of the second resistance path (54). [7] Temperature sensor (40) according to claim 6, wherein the first resistance path (53) is a mirror image of the second resistance path (54) and the first resistance path (53) has the same geometric shape, cross-sectional area and path length as the second resistance path (54). [8] Temperature sensor (40) according to claim 4, wherein the reference electrode (48) is porous, wherein the reference electrode (48) has a permeability of the same order of magnitude as the permeability of the porous separator (20).

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